While I think we all understand now that Joseph7820 had a lousy cruise it doesn't help to tell someone else that they made the wrong choice and that they should have booked another line.
Clizme, we took our two daughers (9 and 17) on the Orchestra. We have been loyal Carnival cruisers and were a little nervous given all that we had heard but we went anyway, just like you should do. You are armed with knowledge and you're doing your own research, now the experience will depend largely on your attitude and those of your daughters. The great thing about taking 3 girls of your own is that they will make their own fun to a degree. The activities for young people on MSC are not as fine tuned as Carnival and there are some things missing but my kids were far from miserable and despite what you read they did have a great cruise. They had access to a lounge and on many nights my eldest danced until curfew then begged to stay out. If you make constant comparisons to Carnival it will ruin your trip, not because Carnival is better but because it is too much of a focus. This is just my opinion mind you, but if you embrace the differences between the lines I think you'll have a blast. The Italian experience for us was better than Costa and my girls loved their "classy" cruise. They met some great pen pals that they are still corresponding with and I think yours will do the same. Go and have a blast.